34 TRANSACTIONS LIVEEPOOL BIOLOGICAL SOCIETY. 



and 8). Inside the ectoderm on this dorsal aspect a very 

 thin layer of connective tissue (parietal mesoderm) can 

 now be recognised (fig. 8, mes). 



We now come upon the posterior end of the stomach. 

 This organ is of large size and complicated shape, it 

 extends from about the 50th to the 160th section. There 

 are two great laterally placed posterior lobes which join 

 anteriorly. Into one of these lobes, the left, the oesophagus 

 opens, while the intestine emerges from the other, on the 

 right side. They may be conveniently referred to as the 

 cardiac (left) and the pyloric (right) sacs respectively. 

 These lateral posterior parts of the stomach are of con- 

 siderable dorso-ventral extent (see PI. 11. fig. 1, st, st'), 

 while the anterior or median part of the stomach where 

 the cardiac and pyloric sacs join is low, but very wide from 

 side to side (PI. II. fig. 5). The greater part of the 

 alimentary canal is richly ciliated (PI. I. fig. 10). I have, 

 however, not been able to find any trace of cilia in the 

 cardiac sac which is very much more glandular, especially 

 in its ventral end (PL II. fig. 1, gl) than any other part of 

 the stomach. 



The pyloric sac extends a little further posteriorly than 

 the rest of the stomach, and is seen in fig 7, PI. I. with 

 the flattened diverticulum from the oesophagus lying 

 dorsally. In the next figure (PI. I. fig. 9), which shows 

 the 61st section, the cardiac sac is just beginning to 

 appear below the oesophagus, and ten sections further 

 forward (PI. I. fig. 10) the two are found to communicate, 

 the oesophagus having turned ventrally with a slight un- 

 dulation. The pyloric sac is now large and lies with its 

 long axis dorso-ventrally. Its interior, and that of the 

 oesophagus, is ciliated while the cardiac sac shows glandu- 

 lar cells at its ventral end (PI. I. fig. 10, gl.). 



The last three figures show the gradual reduction in 



